examples: calc++: a Makefile and a README

* examples/calc++/Makefile, examples/calc++/README: New.
* examples/calc++/local.mk: Ship and install them.
* doc/bison.texi: Formatting changes.

examples/calc++/README

@@ -0,0 +1,51 @@
+This directory contains calc++, a simple Bison grammar file in C++.
+
+Please, read the corresponding chapter in the documentation: "A Complete C++
+Example".  It is also available on line (maybe with a different version of
+Bison):
+https://www.gnu.org/software/bison/manual/html_node/A-Complete-C_002b_002b-Example.html
+
+To use it, copy this directory into some work directory, and run `make` to
+compile the executable, and try it.  It is a simple calculator which accepts
+several variable definitions, one per line, and then a single expression to
+evaluate.
+
+The program calc++ expects the file to parse as argument; pass `-` to read
+the standard input (and then hit <Ctrl-d>, control-d, to end your input).
+
+$ ./calc++ -
+one := 1
+two := 2
+three := 3
+(one + two * three) * two * three
+<Ctrl-d>
+42
+
+You may pass `-p` to activate the parser debug traces, and `-s` to activate
+the scanner's.
+
+-----
+
+Local Variables:
+mode: outline
+fill-column: 76
+End:
+
+Copyright (C) 2018 Free Software Foundation, Inc.
+
+This file is part of Bison, the GNU Compiler Compiler.
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# LocalWords:  mfcalc calc parsers yy MERCHANTABILITY